Contact toasting of buns has been offered to the commercial food service market for a number of years. The method of moving product in a conveyor across a hot surface to toast the product is referred to as conveyor bun grilling. This grilling method requires the bun to be pressed against the hot surface as it is moved along the conveyor, to provide quick, even toasting.
Horizontal grillers having a heated bun discharge and holding area are known in the art. These grillers preferably utilize a spring tension track support to apply pressure to the bun, to ensure even and adequate grilling. However, grillers of this design have been subject to certain limitations. For example, while the spring tension track support provides a more uniform toasting of the cut side of the bun, by pressing the cut surface firmly and evenly against the grilling surface, it also leaves markings on the exterior of the bun. The pressure applied by the spring tension track support creates these markings on the rounded surface of the bun These markings can be considered to be aesthetically undesirable.
Accordingly, a conveyor bun griller is needed that can effectively grill the cut surfaces of a bun, without creating undesirable markings or impressions on the exterior of the bun.
Different wire type conveyor belts having tighter spacings were evaluated in attempting to reduce the incidence of bun marking. The belt with the tightest spacing tested was a wire mesh belt that was 90% closed. These wire mesh belts were heavy, however, which reduced the ability of the spring track to conform to the shape of the bun. Moreover, the metal conveyors continued to cause an impression or conveyor mark on the bun, and accordingly, were not satisfactory.
Next, attempts were made to cover the existing wire conveyor with a belt material. Due to the high operating temperature of the conveyor, a polytetrafluoroethylene sheet material was selected. This material is also the preferred material for use on the hot top platen griller surface. While the results were positive--the wire belt markings were eliminated--the smooth, slick surface of the polytetrafluoroethylene material caused problems with the feeding of the bun. Upon initial infeed, the bun would not enter the area between the upper hot platen and the lower conveyor belt without manual assistance. Once the bun was between the platen and conveyor, the bun would move, maintaining contact to toast when set at minimum pressure. However, as pressure would be applied to increase the toasting results, the compression would cause the bun to stall on the slick track surface.
Accordingly, a conveyor bun griller is needed that can prevent markings on the exterior of the bun, while conveying the bun reliably, without catching or stalling. The goal is to maximize the initial pressure applied to the bun while the bun is most resilient ("preferably below about 1300F.). This allows for maximum heat transfer. Once the bun absorbs heat the softened product will deform. Thus, the compression by the belt is reduced at the end of the cycle.